In the field of microfabrication such as production of integrated circuit devices, photolithographic technology that enables a reduction in line width has been desired in order to achieve a higher degree of integration. However, it is considered that it may be very difficult to implement sub-quarter-micrometer microfabrication using near ultraviolet rays such as an i-line. Therefore, use of radiation having a shorter wavelength has been studied in order to enable microfabrication with a line width of 0.10 μm or less, for example Examples of such short-wavelength radiation include a bright line spectrum of a mercury lamp, deep ultraviolet rays (e.g., excimer laser light), X-rays, and electron beams. In particular, KrF excimer laser light (wavelength: 248 nm) and ArF excimer laser light (wavelength: 193 nm) have attracted attention. Various photoresist film-forming radiation-sensitive resin compositions suitable for use with such short-wavelength radiation have been proposed.
Liquid immersion lithography that exposes a photoresist film via an immersion medium (e.g., water) having a refractive index higher than that of air has been proposed in order to form a finer pattern. When using liquid immersion lithography, a photoresist film formed on a wafer and a lens of an exposure system come into contact with an immersion medium (e.g., water). Therefore, the immersion medium may permeate the photoresist film, and may reduce the resolution of the photoresist. Moreover, the component of the photoresist film may be eluted into the immersion medium, and may contaminate the surface of the lens of the exposure system. In order to solve the above problems, a method that forms an upper-layer film (i.e., protective film) on the photoresist film in order to isolate the photoresist film from the immersion medium, and an upper-layer film-forming composition used for the above method have been proposed (see Patent Document 1, for example).